Some motor graders, for example, in recent years are provided with an all-wheel drive device for driving all of the front and rear wheels. Such an all-wheel drive device transfers engine output to rear wheels through a transmission so as to drive the rear wheels, and also transfers engine output to a hydraulic pump so as to drive each of right and left front wheels using corresponding one of paired hydraulic motors rotatable with discharged oil from the hydraulic pump.
Japanese Patent Laying-Open No. 2011-106611 (PTD 1) discloses a configuration of a power train including a hydraulic motor, a first planetary gear reducer, and a second planetary gear reducer, the power train being configured to transfer a torque of the hydraulic motor to a wheel through the two-stage planetary gear reducer, where a hydraulic clutch mechanism is coupled to a carrier of the second planetary gear reducer so as to prohibit or permit rotation of the carrier.